Migrate new company mailbox to our Tenant

[ali ali]

Hello ,

we are in hybrid Exchange +AAD Connect + OFFICE 365 with a Headoffice.com Domain .

we purchase a new company (B) and thez are in Onmpremise infrastructure ( AD+Exchange).

our Goal to migrate their mailboxes to our office 365 Tenant and thez will keep the management of their Active Directory .

what can be the best solution ?

Best Regards

[#2]

@ali ali 

- First get ownership of the company's domain.

- You will need to add Company B's domain as a an accepted domain and validate it in Office 365. 

- Create a One Way trust in AD 

"External trust: You will create an external trust only if the resources are located in a different Active Directory forest. An external trust is always nontransitive and it can be a one-way or two-way trust."

- Replicate those accounts to Office 365 via Azure AD connect

-or-

- Get a export of their AD user list and recreate in your on-premise AD and put a DC on the Company B's site. 

- From Company B's on-premise exchange, you can do a .PST export of all mailboxes and upload it to the Azure blob spot, then use the .PST import mapping file to upload it to the respective mailboxes. 

Let me know if you have any questions.

Ash, MCE

[#3]

@Ash365 

 First get ownership of the company's domain.

- You will need to add Company B's domain as a an accepted domain and validate it in Office 365. 

-->ADD to the company B domain in our Exchange as accepted domain and add it in office 365

- Create a One Way trust in AD 

"External trust: You will create an external trust only if the resources are located in a different Active Directory forest. An external trust is always nontransitive and it can be a one-way or two-way trust."

is it necessary this trust ? there is no way to do it without trust ?

- Replicate those accounts to Office 365 via Azure AD connect

-->is it possible to configure AAD connect with multiforest ?how can i do it ?

-or-

- Get a export of their AD user list and recreate in your on-premise AD and put a DC on the Company B's site. 

- From Company B's on-premise exchange, you can do a .PST export of all mailboxes and upload it to the Azure blob spot, then use the .PST import mapping file to upload it to the respective mailboxes. 

-->Pleae could tel me how ? it's important

Regards

[#4]

Trust is not necessary. In many cases however, the organization would like to manage users from both tenants from a central point, so you might even consider a merge of the two AD forests to meet that goal. Another option is to first do the migration, then at some point create accounts for the migrated users in your AD and "match" them against O365.

[#5]

Hello,
How could I do migration in this case?

[#6]

Syncing Multiple Forests to O365 using Azure AD Connect:-
https://docs.microsoft.com/en-us/azure/active-directory/hybrid/plan-connect-topologies#multiple-fore...

For PST Migration follow this:- https://docs.microsoft.com/en-us/office365/securitycompliance/use-network-upload-to-import-pst-files
There are third party tools available as well for this.